This invention relates to a bending device for use in an endoscope or the like.
As is well known, an endoscope comprises a hollow body, a flexible insertion portion extending from the front end of the body, a flexible bending portion extending from the distal end of the insertion portion, and a rigid portion formed on the distal end of the bending portion. An inspection window and an illumination window are formed at the rigid portion. A manipulation dial is mounted on the body, and is connected to the bending portion through an operating wire. The manipulation dial is angularly moved to bend the bending portion so that the inspection window, formed at the rigid portion, can be directed to a desired direction. The bending portion comprises an articulation assembly constituted by a series of segments angularly movably connected to one another.
Japanese Patent Publication No. 631/77 discloses an articulation assembly. Each of segments constituting this articulation assembly has a semi-cylindrical portion, and a pair of auxiliary tubular portions of a very small diameter formed respectively on the opposite circumferential ends of the semi-cylindrical portion. A number of segments are disposed along a line in such a manner that the semi-cylindrical portions of any two adjacent segments are directed in opposite directions, respectively, with the auxiliary tubular portions of one of the two adjacent segments aligned respectively with the auxiliary tubular portions of the other segment. A pair of limiting wires are passed respectively through the oppositely-disposed two rows of aligned auxiliary tubular portions to interconnect the segments in such a manner as to prevent the segments from moving radially relative to one another. A guide portion is formed on the circumferentially central section of the semi-cylindrical portion of each segment which is circumferentially spaced 90.degree. from the auxiliary tubular portions, and an operating wire is passed through the guide portions of the segments.
In the articulation assembly of the above construction, since the segment has the auxiliary tubular portions of a very small diameter formed respectively at the opposite circumferential ends thereof, a plate or strip of relatively soft metal must be used when the segment is formed by bending the metal plate. Therefore, when a compressive force is applied to the segment in the radial direction of the segment, the segment is liable to be deformed into a flattened configuration, and various parts received inside the segments are compressed, and in the worst case, such parts may be damaged.
The prior art includes Japanese Laid-Open (kokai) Patent Application No. 130025/83 which shows in FIG. 7 an articulation assembly comprising a number of cylindrical segments. The segment has two pairs of engaging portions. One pair of engaging portions are radially opposed to the other pair of engaging portions. Each pair of engaging portions are spaced from each other in the axial direction of the segment. Each engaging portion has a pair of pieces projecting from the edge of the segment in the axial direction of the segment. One of the pair of pieces slightly projects radially outwardly from the outer peripheral surface of the segment, and the other piece slightly projects radially inwardly from the inner peripheral surface of the segment. The engaging portions of any two adjacent segments are engaged with each other to form the articulation assembly.
Japanese Laid-Open Utility Model Application No. 10605/80 discloses a segment in the form of a flat plate, and this segment has a pair of V-shaped notches, and the notches of any two adjacent segments are engaged with each other.